Cutting teeth for well drills



scoTT I 2,340,492

FOR WELL DRILLS Feb. 1, 1944.

CUTTING TEETH Filed Sept. 21, 1940 INVENTOR.

fig 0'1 600 W E M 1 ATTORNEYS.

Patented Feb. 1, 1944 CUTTING TEETH FOR WELL DRILLS Floyd L. Scott,Houston, Tex., assignor to Hughes Tool Company, Houston, Tex., acorporation of Delaware Application September 21, 1940, Serial No.357,725

Claims.

My invention relates to the forming of the cutting teeth upon welldrills and more particularly the type of well drill employing two ormore approximately conical shaped cutters. Such well drills areordinarily termed cone drills" in the field and the cutters are referredto as cones.

It is an object of this invention to provide a tooth formed upon thecutting surface of the cone which will more effectively engage and cutaway the formation being drilled.

It is a further object to mount the cutters upon which the teeth areplaced in such manner that the teeth will have a plowing action on thewell bottom and thus more effectively disintegrate the material.

It is a further object of the invention to space the teeth upon the conesurface in such manner as to provide space into which the material beingcut maybe displaced and thus more readily Washed away by the flushingfluid.

It is a further object to provide a cutting tooth which may engage theformation with a sharp cutting edge and more readily penetrate into thebottom of the hole.

For a better understanding of the invention reference is made to thedrawing herewith wherein,

Fig. 1 is a top plan view of the bottom of the hole showing somewhatdiagrammatically the position of the cutters upon the bottom.

Fig. 2 is a view showing one of the cutters in side elevation positionedupon the bottom of the hole, and having teeth embodying my invention.

Fig. 3 is a perspective view of a cutter tooth embodying one form of theinvention; and

Fig. 4 is a similar perspective view illustrating a slightly-differentform of cutting tooth.

Well drills embodying cutters of the general character upon which myinvention is applied are well known in the art. A cutter such as shownat A is mounted rotatably upon a shaft l projecting inwardly anddownwardly from its support upon a drill head 2. When an approximatelyconical shaped cutter is mounted in this position the conical surface ispresented downwardly toward the well bottom and tends to disintegratematerial as the cutter is rolled upon the bottom of the hole.

The cutters are normally provided with a row of heel teeth 3 adjacentthe base of the cone, this row of teeth being relatively long and havingthe teeth chisel shaped, with a cutting crest 4 thereon. Between the rowof heel teeth and the apex are teeth 5 which cut the bottom of theldiolfi adjacent the inner axis of rotation of the In previous forms ofwell drills of this character it has been common to offset the axis ofrotation of the cutter from the axis of rotation of the drill. Thisoffset has been slight and in the amount of only a fraction of an inch.This offset of the cutter axes from a true radial position has beenemployed to get a slight deviation from a true rolling motion of thecutters. The teeth are thereby given a slight scraping or twistingaction on the bottom, which assists in disintegrating the material.

In the present invention the axes 6 of the cutters have been swungaround until they are tangent to a. comparatively large circle having adiameter of two or three inches. This exaggerated offset places thecutters so that they engage the well bottom in an entirely differentmanner than when the cutters are offset in the old manner previouslydescribed. Thus, when the cutters are placed as shown in Fig. 1,relative to the bottom of the well, it will be seen that'as the drill isrotated in a righthand direction the cutters have only a slight lateralthrust against them, tending to cause them to rotate and the relativespeed of rotation of the cutters will be greatly reduced. The progressaround the bottom of the hole will be at the same speed as previouslybut the cutters will rotate upon their axes during the time it istraversing the well bottom at a very slow rate. Also, the teeth upon thecones will be presented against the formation so that the inner ends orsides of the teeth will engage the material rather than the slopingflanks of the teeth employed in the previous types of bits. The ends ofthe teeth will, therefore, have gouging action rather than the oldchisel contact on bottom.

The improvement in this application includes the shaping of the teeth onsuch a drill in such manner that the forward advancing side of the toothis adapted to plow into the formation, and thus more effectivelydisintegrate the material.

With reference to Fig. 2, it will be noted that the teeth 5 are formedwith the advancing side thereof convex, so that it acts somewhat as thepoint of a plow moving the formation on bottom to either side and intothe space around the tooth. In Fig. 2 it will be noted that there arespaces such as indicated at 8 around the teeth so that material may bemoved away from the tooth into this space and thus be washed away by theflushing fluid. On the rearward or receding side of the tooth the facemay be concaved, as shown at I, in Figs. 2 and 3.

Also, it will be apparent that the invention may be carried out byconstructing the teeth angular in cross section as shown in Fig. 4. Inthis embodiment the plowing action on the bottom will be morepronounced. In the angular type of tooth the forward pointed face 8 isreferred to as the convex side.

When a cutter having teeth of this formation thereon is moved about thebottom of the hole imthe manner shown in Fig. 1, the convex side of theteeth on the cutter are presented in a position toward the formationbeing cut. The cutter does not advance with its axis directed exactlyforward and the cutter will, therefore. tend to rotate at a slow speedupon its axis as the cutter traverses the bottom of the hole.

With the tooth formed in this manner and with the cutter rotating itwill be clear that the tooth not only has a plowing action but has acutting action of the edges of the teeth as the cutter rotates. By theuse of cutters with teeth thus formed an action on the bottom isobtained which is materially different from the action of chisel-shapedteeth of the approximately true rolling form of cone. Such prior teethwere adapted to roll in such manner that the chisel edge engages thebottom with a downward chisel stroke to form impressions, commonlycalled rock teeth, thereon. A more effective cutting action is obtainedthrough my improved construction in which the rounded sides and crestscontact the formation.

This type of cutter is intended for semi-hard and softer formations andin such formations it excells in cutting action the types of teethnormally employed upon bits of this character.

As will be obvious, this invention is particularly adapted for use oncutters mounted for operation with their cutter axes offset asdescribed, but such teeth are not limited for use upon cutters somounted and may be effectively employedon cutters mounted in the normalmanner with the cutter axes approximately radial.

What is claimed is:

1. In a well drill having thereon a plurality of rolling cutters ofapproximately conical shape, the apices of said cutters being pointedforward side and spaced' apart on the cutter surface and formed with theconvex side rounded transversely and presented forwardly in thedirection of rotation so that it will engage and plow into the bottom ofthe hole.

3. In a rotary well drill having thereon a plurality of rolling cuttersof approximately conical shape, the improvement comprising teeth on saidcutters formed convex on the side toward the apex of the cutter andconcave on the other side thereof, said sides being convex and concavefrom the base to the crest thereof in the direction extendingtransversely of said teeth.

4. In a rotary well drill having thereon a plurality of rolling cuttersof approximately conical shape, the improvement comprising teeth on saidcutters formed convex on one side and concave on the other side thereof,said sides being convex and concave from the base to the crest thereofin the direction extending transversely of said teeth, the cutters beingso mounted as to present the'convex faces of said teeth forwardly in thedirection of rotation of said drill.

5. In a rotary well drill having thereon a plurality of rolling cuttersof approximately conical shape, said cutters being offset relatively tothe axial center of the hole to point the smaller end of the cutterapproximately forwardly in the direction of rotation, the improvementcomprising teeth on said cutters formed convex on the side toward thesmaller end of the cutter and concave on the other side thereof, saidsides being convex and concave from the base to the crest thereof in thedirection extending transversely of said teeth, the crests of said teethbeing extensions of the convex side and rounded so as to plow into theformation.

FLOYD L. SCO'I'I.

